It has long been generally recognized in the art that copper and copper alloys present a bonding problem because of the rapid oxidation of copper which results in a weak copper oxide surface. The establishment of satisfactory bonds is particularly difficult if high shear and high peel strengths are required. The problem attends in the production of components of electrical apparatus such as connection rings in which resin materials are used to bond copper strands and to solidify the structure. In the case of terminal studs of collector assemblies, hydrogen leak problems are a consequence of poor bonding of insulation to copper surfaces.
A number and variety of different methods have been devised by others heretofore in efforts to overcome or alleviate the copper bonding problem, but they all involve significant disadvantages. For one thing, they share a critical time requirement complicating work flow in production because of the necessity for applying the resin coating immediately on completion of copper substrate surface preparation. Further, those processes--specifically, the ammonium persulphate process, the ferric chloride process, the hydrochloric acid-ferric chloride process, the sodium dichromate-sulphuric acid process and the so called "black oxide" process--involve the use of highly corrosive and dangerous materials and consequently require special care in compliance with governmental safety, health and environmental protection laws and regulations.